Isolation Of Sulfate-reducing Bacteria Research Articles

Media for the detection of sulphide-producing bacteria in industrial water systems

The importance of sulphate-reducing bacteria (SRB) in microbiological induced corrosion (MIC) has been widely recognized for many years [1]. There are many formulations of culture media used for enumerating SRB [2,3]. Previous studies indicated that viable count procedures underestimated the in situ population by a factor of approximately 1000 compared to in situ sulphate reduction activity [1,4]. The aim of this study was to evaluate different isolation media and carbon sources for the isolation and detection of SRB in South African industrial water systems. Modified iron sulphite (IS) medium yielded the highest numbers when used to enumerate SRB from pure cultures and industrial water samples. When comparing API, SABS, IS, Oxoid and modified synthetic medium using pure cultures of Desulfovibrio desulfuricans IS-medium gave a 12.1%, 40%, 53.3% and 60.3% higher recovery than SABS-, Postgate-, API- and synthetic medium, respectively ( p < 0.05). IS-medium gave a 20.1%, 61.8% and 100% higher recovery than SABS-, API- and Oxoid medium, respectively, when using pure cultures of Desulfotomaculum orientis ( p < 0.05). The dominant sulphide-producing bacteria isolated from the industry using IS-medium were facultative aerobic gram-negative rods that were able to produce sulphide from sulphite under strictly anaerobic conditions. IS-medium was therefore not selective for SRB only. H 2S-producing bacteria that utilized lactate, acetate, formate or palmitic acid as different carbon sources were also isolated from industrial water samples when using synthetic medium.

Monitoring the enrichment and isolation of sulfate-reducing bacteria by using oligonucleotide hybridization probes designed from environmentally derived 16S rRNA sequences

A fluorescently labeled version of a population-specific oligonucleotide hybridization probe was used to monitor the enrichment and isolation of a sulfate-reducing bacterium from a multispecies anaerobic bioreactor. The organism was originally identified as a molecular isolate that was phylogenetically related to Desulfovibrio vulgaris by amplification and sequencing of part of its 16S rRNA sequence. The sequence, in turn, was used to design a population-specific probe. The anaerobic medium used for the organism's enrichment and isolation was based on the physiological properties of the its closest relatives as identified by sequence comparisons. Of 30 isolates examined, only 3 hybridized with the probe. Nearly complete 16S rRNA sequences determined for each of these three isolates (i) had no mismatches with the probe target site, (ii) were identical to the amplified partial sequence of about 500 nucleotides and to one another in all other positions, and (iii) were 93.9% similar to that of D. vulgaris. In addition, one isolate chosen for further study (strain PT-2) had a substrate specificity comparable to that of D. vulgaris. These results confirmed that polymerase chain reaction amplification of 16S rRNA sequences from environmental samples can be accurate and can also provide phylogenetic information from which aspects of a population's physiology can be inferred.

Interaction of cyanobacteria and sulfate-reducing bacteria in subsurface black-layer formation in high-sand content golf greens

Two Oscillotoria spp and a Nostoc sp., and a culture including Desulfovibrio species, were isolated from the surface and subsurface of high-sand content golf greens which contained subsurface black globules and layers often associated with the death of turf. These isolates and a pure culture of D. desulfurleans were grown for 12 weeks on calcareous sand columns treated with nutrient salts alone or in combination with CaCO 3, gypsum, sulfur, chelated iron, or chelated iron + S. The Oscillatoria spp slowed water flow in response to most treatments and prevented water now through the sand after 12 weeks in response to S, chelated iron, and chelated iron + S. Nostoc slowed water flow in response to all treatments, and sulfate-reducing bacteria slowed water flow slightly in response to chelated iron. None of the cyanobacteria or sulfate-reducing bacteria isolates alone developed any blackening of the sand columns. Only sand columns on which any of the cyanobacteria isolates were grown for 12 weeks and then infested with either of the sulfate-reducing bacteria isolates developed varying degrees of blackening in the subsequent 12 weeks. Blackening was most intense in response to S, chelated iron, and chelated iron + S. It was concluded that a natural interaction exists between the cyanobacteria and sulfate-reducing bacteria that produces black subsurface globules and layers in high-sand content golf greens, and that the interaction is stimulated by the management practices applied to these greens.

Enumeration, isolation and identification of sulphate-reducing bacteria of anaerobic digestion

A method was developed for the enumeration and isolation of the sulphate-reducing bacteria in the anaerobic digestion of raw sewage sludge. This method differed from conventional methods used for the enumeration and isolation of sulphate-reducing bacteria in that anaerobiosis was achieved by the use of media with a low redox potential in stoppered bottles containing oxygen-free gas atmospheres. Carbon dioxide—bicarbonate buffer systems were employed in the media. Sulphate-reducing bacteria occurred in numbers of 3–5 × 10 4/ml in a raw sewage sludge digester. Seven pure cultures of sulphate-reducing bacteria were isolated from digesters and all proved to be Desulfovibrio desulfuricans. No evidence for the presence of Desulfotomaculum ssp. was found. The role of sulphate-reducing bacteria in the anaerobic digestion of raw sewage sludge is discussed.